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[relax24]

And FAKE COUNTERFREIT chips arghhh! I suspect my 18f2520 is also fake (aliexpress) because I always use cellulose thinner for cleaning boards and I use last time on my building meter on the ic black color become matte black and white cotton become a black . MCP601s and LM311 looks good.I search on aliexpress parts examine sellers picture and spend a lot of times and find candidates to buy then I send message to each seller if I buy they are send me exactly in like picture or not and still some of came different or fake. I am buy earlier ft2232rl from aliexpress and came original and I say to seller this and request 5 more to exactly same chip but last 5 ic's are came fake, I always buy realy important parts in digikey but cause much expensive costs of course.

[Ruslan]

I bought my 18F2520 chips and other OpAmps from Futurlec.com , at the time I was not aware of AliExpress. Was not cheap, but at least I didn't receive any fakes from them ... yet...
I'm not sure which firmware is the latest and which schematics for RLC-2. They are some guys who constantly improving that project even after it finished long time ago (that's why you may find it confusing). One of my friends made a collection of data regarding those meters http://kripton2035.free.fr/LCR%20meters/lcr-go-russian.html

[relax24]

Hi friends, "ruslan" and "R2-D2" , I am still install and try some parts, my oscillator about up to 900khz (author says 700-800khz good area)and jump drift up and down, I try to all 113 page read again in google translate then I am found if C1 and L1 not good then this happens mostly and I am buy and try some inductance and good capacitance later, also somehow my 50ma source sometimes jump and drift a little bit 49.7 +-0.2ma. I was made a mistake in layout drawing relay driver pins because in schematic relay pin names not same in PK-5 datasheet and I accept relay pin sides as exactly in schematic then I draw for TQ2Sa-L2-5V , I swap driver transistors to relay drive legs and fix the problem (I am reversed relays set and reset conditions).

When I read all pages from to start I see this message from author
page 76 authors message "# 389766 "

and if I am understand correctly (~ 6.0) value in description pdf actually amps gain values but no any explanation to how can we properly measure or calculate these values. In my pictures (I also find random online opamp gain calculator and calculate my values) first opamp c_adc, second r_adc,

1- Can we calculate (in red area in the picture) or measure(with series input output 1k resistors) to gain then write in setup menu?

2- and these measurements or calculations
for amp1=point "D" to "E" (looks easy understanable) (in my examle gain=6)
for amp2=point "D" to "F" (2 amp gain serial in my examle gain=12) or "E" to "F" (only amp2 gain in my examle gain=6)
I ask because two gain stages become a serial, so is the "measurement point to r_adc" author says in message, this means 2 opamp serial gain calculation, am I right? or just only amp2 gain must be set and write in setup?
If we adjust R3 and R8 screen readings change and also we adjust amp1 amp2 in menu also change, not easy to catch correct gain stage and write in menu I guess. Sorry for my poor English.

Присоединённое изображение (Нажмите для увеличения)

[relax24]

This is gain calculator results

Присоединённое изображение (Нажмите для увеличения)

[Ruslan]

1. Generation frequency for LM311 is better to keep below ~800 KHz (inductor may need to be changed (increased value) or capacitor. That's for better stability. But you cannot get of rid of it completely (it is not a quarts oscillator), you can only reduce it. For better precision, do the calibration right before measurements.

2. 50 Ma current source is actually drifting that much, you are not alone. That problem with drift is not easy to fix (that's why in next version of the meter that current was reduced down to 10ma). After warming up drift is becoming lesser, and current is not drifting that much.

3. Your calculations are correct, but you don't need trimpots to set amp ratio to 6 (I did it with just regular precision resistors (1%). Final calibration is done in menu by adjusting those 2 Amp settings after series of measurements of resistors (you will need as precise test resistors as you can get for that purpose).

Это сообщение отредактировал Ruslan - Dec 6 2018, 07:44 AM